The present invention relates to therapy and training equipment for constrained knee-joint movement with a lower leg accommodating arrangement and a guiding arrangement, which arrangements can be rotatably connected to one another via an articulated device.
1. Background of the Invention
Knee injuries and the associated knee operations frequently require a prolonged immobilisation of the knee-joint, which leads to a general weakening and impairment of the leg musculature and to restrictions in movement. Appropriate medical aids are therefore used in the treatment of knee injuries or in the post-operative period, which are designed to reduce the restrictions in movement or to counteract, by performing specific movement exercise, the incidence of restricted movement.
Particularly after a crucial ligament operation so-called motor driven rails are used to rehabilitate the joint. These motor driven rails serve to accommodate the injured leg and are provided with a drive device that permits a rotation of a lower leg receptacle relative to a thigh receptacle. This produces a knee-joint, movement, substantially free of any weight loads, so that the mobility of the knee joint can be trained without any damaging weight loads on the ligaments. The disadvantage of the known motor-driven rail is that, on the one hand, a drive (generally an electrical drive) is required to move the motor driven rail, and on the other hand the healthy leg is not involved in the movement, with the result that, particularly in the case of prolonged rehabilitation measures, there is a needless weakening and impairment of the musculature of the healthy leg. With a motor driven rail only a passive exercising of the musculature and tendons is thus possible. Furthermore, motor-driven rails are expensive to purchase on account of their motorised drive, which makes it difficult to carry out such rehabilitation measures, desirable per se, except in hospitals and clinics with technically sophisticated equipment and a corresponding procurement budget. Also, patients have found it difficult to handle and adapt individually to motor driven rails, with the result that these activities generally have to be carried out by trained care staff.
Cable pull arrangements are known, which are substantially simpler devices and can be used for movement therapy on a knee joint, and can be installed on a frame device at the patient""s bed and, when coupled to a cable pull, can facilitate movements of the injured leg initiated by the health leg. However, a disadvantage with such cable pull arrangements is that the movement coupling between the healthy leg and the injured leg is not kinematically unambiguous, in other words it does not take place in a constrained manner, and for example there are degrees of freedom of movement in the direction opposite to the cable pull direction or even transverse thereto, which can allow movements that are harmful for the rehabilitation of the knee-joint.
Such cable pull arrangements are therefore also unable to replace the aforedescribed complicated and costly motor-driven rails.
2. Background of the Prior Art
This object is achieved by a device and equipment having the features of claim 1.
In the device and equipment according to the invention the guiding arrangement cooperates with the lower leg accommodating arrangement in such a way that, on a rotational movement of one of the lower legs.
By coupling the lower leg accommodating arrangement, which serves to receive the patient""s lower leg, to a guiding arrangement, which permits a movement of the lower leg simply along a predetermined movement path, an exactly defined knee-joint movement is provided that excludes damaging loads on the knee-joint. In the therapy and training equipment according to the invention the drive for the load-free movement of the injured leg is provided by a force actuated movement of the healthy leg, with the result that on the one hand an external drive can be dispensed with, while on the other hand the healthy leg at the same time experiences a specific training effect to strengthen the leg musculature, the movements of both the injured leg and healthy leg constituting an effective prophylaxis against thrombosis.
The expression xe2x80x9clower leg accommodating arrangementxe2x80x9d used here is intended also to include the possibility of fixing the lower leg for instance on the outside, lying on a rail like device. The essential point is to fix the lower leg in a defined manner that allows the aforedescribed movement sequence.
Advantageous embodiments of the equipment according to the invention are the subject of claims 2 to 4.
In the embodiment according to claim 5 the guiding arrangement is designed as a thigh receptacle, and the lower leg receptacle serves for the movement-coupled accommodation of both lower legs in such a way that, on rotational movement of one of the lower legs, the other lower leg is constrained to move as a result of the knee bending movement. With this therapy and training equipment a force-free movement of the injured leg can thus be achieved by a force actuated movement of the healthy leg. Through the coupled movement of the healthy leg and injured leg the injured leg is constrained to move during the movement of the healthy leg.
In this way it is on the one hand possible to dispense with a motor drive to effect a load-free movement of the injured leg, while on the other hand the musculature of the healthy leg is trained and toned up by the use of the healthy leg to xe2x80x9cdrivexe2x80x9d the injured leg. In addition there is a propioceptive beneficial effect for the sensory motor control of the injured knee-joint.
In addition to the use of the therapy and training equipment to treat an injured leg, the said equipment can also be used purely as a training or sports equipment to train and tone up the leg musculature of both legs.
If, as is the case in a preferred embodiment, the articulated device is arranged so that its rotational axis is coaxial with the rotational axis of the knee-joints, this ensures that the knee joints are not subjected to turning moments and transverse forces that would otherwise occur if the two rotational axes were not coaxial.
It has proved particularly advantageous if the lower leg receptacle is provided in the heel region with a sliding or roller guide so that it is possible for the lower leg receptacle to slide over a suitably shaped underneath surface when the knee joint moves. This arrangement enables the therapy and training equipment to be used when the patient is supine, i.e. when the patient""s buttocks and heels lie substantially in one plane and movement of the injured leg is effected by bending the healthy leg. Especially when using a roller guide, which places fewer demands on the flattest possible shape of the aforementioned underneath surface, the therapy and training equipment can thus be used in a patent""s bed.
In order to set and adjust, a specific knee-bending range that is formed to be particularly advantageous for the treatment of the injured leg, the articulated device of the therapy and treatment equipment can be provided with two varying angle stops.
It has proved to be particularly advantageous, especially when using the therapy and training equipment in the patient""s bed, if the articulated device is provided with a fixing and locking device for the variable adjustment of a fixed knee-bending position. In this way it is possible to lock the articulated device in a knee-bending position comfortable for the patient in question and thereby establish a rest position in which the patient can remain for a relatively long time without experiencing unpleasant tensions and strains, and without having to remove the therapy and training equipment, beforehand and re-install it when the movement therapy is resumed. This turns out to be particularly important since such therapies are often performed in so-called interval or staggered mode, with more or less long pauses between successive movement sections.
If the articulated device is provided with a movement counter, which may for example be in the form of an inductive rotational angle sensor, it is thereby particularly simple to monitor the movement training carried out with the therapy and training equipment.
In order to be able to influence the load acting on the healthy leg during the movement training, a loading device, which in a particularly advantageous embodiment is a spring device, can be arranged to act between the thigh receptacle and the lower leg receptacle. By simply adjusting the spring pretensioning, the spring device permits an accurate presetting of the load acting on the healthy leg during the movement training of the injured leg.
In a simple and consequently particularly advantageous embodiment the spring device may be designed as a cable pull spring, i.e. as a resilient and elastic cable. In another embodiment of the therapy and training equipment, a compression spring may be provided. Accordingly, in the first case it is possible to load basically the knee-bending muscle, and in the second case there is the possibility of loading and suitably training basically the knee-stretching muscle, so that a differentiated muscle training can be performed on the healthy leg.
As regards the movement training for the injured leg or knee-joint as well as the muscle training for the healthy leg, the therapy and training effect can be further improved if, in addition to the loading devicexe2x80x94which in a particularly advantageous embodiment is in the form of a spring devicexe2x80x94a damping device is actively provided between the thigh receptacle and the lower leg receptacle. In this way it is possible to execute a movement that is uniform as regards the movement speed, i.e. is isokinetic.
In order to be able to compensate possible incorrect settings of the patient""s injured and/or healthy leg, which can lead to tensions in the knee region if the lower legs are immobilised in a certain position, the lower leg receptacle may be provided with at least one guide adjustable as regards its arrangement relative to the lower leg receptacle. Overlapping superimposed movements of the lower legs are thereby possible on bending the knee, so that the thighs can move not only in a plane of rotation, but also at right angles thereto.
The lower leg receptacle as well as the thigh receptacle can be formed like a capsule, for example from plastics material, and provided with guides for the longitudinally alterable accommodation of rotating arms connected to the articulated device. It is particularly advantageous if the guides are formed integrally in the lower leg receptacle and the thigh receptacle. On the one hand this reduces the number of parts involved in the therapy and training equipment, and on the other hand correspondingly reduces the work involved in assembling the therapy and training equipment.
If the articulated device is designed so that two rotating joints arranged in the outer region of the knee are provided, on which in each case two rotating arms are arranged for connection to the thigh receptacle and the lower leg receptacle, a particularly torsionally rigid form of the therapy and training equipment is provided with minimal effort, and cost.
With regard to ensuring a small number of paris, it has also been found particularly advantageous if a thigh securement device provided to secure the thigh to be thigh receptacle is designed so that, it can be used alternately for both thighs. The same comments also apply to a lower leg securement device.
In order to adjust a loading preset by the spring device, at least one spring coupling point may be designed so as to be adjustable.
The embodiment according to claim 22 has a guiding arrangement designed as the rotating joint axis of a rotating joint arrangement. The rotating joint axis can be altered in its relative arrangement with respect to a patient""s hip-joint rotation point. Lower leg receptacles are coupled to the articulated joint arrangement, the said receptacles being coupled as regards their movement in such a way that a rotational movement of one lower leg receptacle about the rotating joint axis produces a rotational movement in the opposite direction of the other lower leg receptacle. By accommodating the patient""s legs in the lower leg receptacles, the constrained rotational movement occurs about the rotational axis of the articulated joint arrangement, so that force directions that are harmful to the knee joint are excluded. The adjustability of the spatial arrangement of the rotating joint axis relative to a patient""s hip-joint rotation point permits a setting of the rotating joint axis congruent with the knee joint rotation points and thus ensures isometric conditions. This too helps to prevent harmful loads, such as occur for example during an axial displacement of the femur over the libia (known as the xe2x80x9cchest of drawersxe2x80x9d effect), acting on the knee joint.
Since in this embodiment the rotational movement of one lower leg receptacle is produced by an oppositely directed rotational movement of the other lower leg receptacle, a bending movement of the healthy leg can be used to produce a corresponding bending movement of the injured leg without having to employ a complicated and costly drive mechanism. By virtue of the aforedescribed movement coupling, the frequency of the knee-bending movements can be controlled by the patient himself at any time up to a discontinuance of the rotational movement, which means that the equipment according to the invention can be used by the patient himself at any time. Just as few trained staff need to be employed to monitor the operation of the equipment since the latter can easily be manipulated by the patient himself at all times. On account of the ease of operation of the equipment and the absence of a drive device, the equipment is also found to be substantially more economical as regards procurement and operating costs.
Instead of a purely passive exercising, as is possible with the known motor driven rail, the equipment according to the invention permits an active exercising with a natural, physiological movement sequence. The reciprocal movement initiated by the movement coupling effect promotes cartilage and tendon formation.
In addition, the equipment can be used without any alteration both as a passive movement appliance and an active training appliance, so that for example with continuing ongoing rehabilitation of the knee-joint the regime can be changed easily and smoothly to an exercise regime involving active movement of the knee-joint.
It is found to be particularly advantageous if the rotational movement occurs in movement range that has a middle position in which the lower leg receptacles have an identical rotation position. In this way the patient using the equipment is able to adopt, in the middle position, a particularly comfortable rest position in which the lower legs are at the same height. It is also possible to leave the equipment connected to the patient between successive treatment sequences without causing any inconvenience for the patient. Indeed, patients often feel comfortable with the legs in a raised position.
This also provides for a particularly good accessibility of knee-joints and legs during treatment, with the result that it is possible for example to check the healing process and the wound or also carry out cryotherapy while the equipment is connected to the patient.
It is also found to be advantageous if the end positions of the rotational movement range can be adjusted relative to the middle position so that the optimum rotational movement range can be adjusted quite specifically to rehabilitate a restricted movement of the knee-joint.
If the mid position of the lower leg receptacles can be adjusted as a rotational angle position with respect to the rotating joint axis of the rotating joint arrangement, a rest position for the patient""s legs can be arbitrarily chosen as required, in which both legs are bent to the same extent in order to take into account in particular the individual patient""s needs.
It is also possible to fix the mid position and/or the end positions of the rotational movement range in order to ensure if necessary that no knee-joint bending movements are possible beyond these positions.
If the movements of the lower leg receptacles are coupled via a rotating joint arrangement in the form of a gear mechanism, a particularly compact design and manufacture of the whole equipment is possible since the rotating joint arrangement is simultaneously used as a force transmission device.
In particular, if it is intended to use the equipment not only as therapy equipment but also as exercise equipment to build up and/or restore the leg musculature, it has been found particularly advantageous to provide a loading device that acts at least in a phase-like manner against the rotational movement on at least one lower leg receptacle. On the one hand the already described effect of the equipment is intensified since the musculature of the healthy leg used to xe2x80x9cdrivexe2x80x9d the movement of the injured leg is at the same time trained. On the other hand the effect is also enhanced since, through the actuation of the healthy leg, the injured leg is passively exercised as a result of the crossed exercising of the quadriceps.
If furthermore the loading device is adjustable, the latter can be matched in a particularly simple way to the capabilities and needs of the patient.
Such a loading device may be formed for example by a suitable spring or spring/damper arrangement.
If the rotating joint arrangement is designed as a gear mechanism to transmit the force between the lower leg receptacles, it is found to be particularly advantageous to provide the rotating joint arrangement or the gear mechanism with a gear loading system. This can be achieved for example by means of a torque brake integrated in the gear mechanism. Here too it is advantageous if the gear load and/or the brake can be adjusted.
If the rotating joint arrangement is coupled to a height adjustment device, it is possible to control the desired rotational movement range not only by adjusting the end positions of the rotational movement of the lower leg receptacles, but also by adjusting the height of the rotating joint arrangement or of the rotating joint axis.
It is also particularly advantageous if the relative arrangement of the rotating joint axis with respect to the hip joint rotation point can be altered along a movement path of the said rotating joint axis. In this way it is possible to superimpose rotational movements of the thighs about the hip-joint rotational axis on rotational movements of the lower leg receptacles about the rotating joint axis and rotational movements of the lower legs about the knee joint rotational axis, in order thereby to be able to simulate particularly realistic movement sequences such as occur during walking or running.
In order to achieve an optimum congruent setting between the rotating joint axis and the knee joint axes, the lower leg receptacles may be made adjustable as regards their alignment relative to the rotating joint axis.
In order to accommodate the lower legs in the lower leg receptacles in a manner particularly comfortable for the patient, the receptacles may be adjustable as regards their length.
Furthermore, the lower leg receptacles may be provided at their free ends with foot rests.
If the foot rests can rotate about an axis transverse to the longitudinal axis of the lower leg receptacles, the rotational movements of the said lower legs can be augmented by rotational movements of the feet about the ankle rotational axis, which produces an effective prophylaxis against thrombosis since the activation of the fibular pump promotes venous blood flow.
If furthermore the movements of the foot rests are coupled in such a way that a rotational movement of one of the foot rests produces a rotational movement in the opposite direction of the other foot rest, it is then for example also possible to use the equipment for movement therapy on an ankle, in a similar way to the movement therapy on a knee joint.
If the movements of the foot rests are coupled to the lower leg receptacles in such a way that a rotational movement of a lower leg receptacle produces a rotational movement in the same or opposite direction of the foot rest arranged on the respective lower leg receptacle, the coupled movement of the lower leg receptacles can at the same time also be utilised for the constrained rotation of the foot rests.
The installation of the equipment on the patient is particularly facilitated if the lower leg receptacles are formed an capsules having at least one securement device arrangement opposite a capsule opening. In this way it is possible to insert the lower legs in the lower leg receptacles and secure them therein with the aid of the securement device.
The utility of the equipment can be improved still further if the securement device is formed as a laterally open strap or hoop so as to permit a lateral insertion or removal of the lower legs.